Read over your own application and any supplemental application, taking special care to recall what you told them about yourself in your personal statement and any essays. Unless it is strictly a closed file, behavioral interview, they WILL ask you questions relevant to your personal statement, so be prepared to back up an interest in say, food animal medicine, with some actual knowledge of what that entails.
Otherwise, read up on the CDC "hot list"of zoonotic diseases, be aware of what is going on in the world around you (more than a few of my classmates were asked about current events that had nothing to do with veterinary medicine), and peruse the school's own web site to get sense of who they think they are, what issues they care about, etc.
But mostly, get a good night's rest, eat a healthy breakfast with protein, and do your best to relax. They are already interested in you. Just be yourself, present yourself professionally, make eye contact, and smile. Consider your answers carefully before you respond. It's ok to say, "I don't know, that's a good question."
Does that help?